The present invention relates to high speed weaving machines, and more particularly, to the heddle frames for use on high speed weaving machines.
In the past, heddle frames used in weaving machines were composed of a pair of end braces and a pair of laterally extending rails. The end braces were conventionally, rigidly attached to the top and bottom rails at each end. The end braces were free to slide in a guiding groove on a support on the weaving machine to form the shed during the weaving operation. With the advent of high speed weaving machines, which make as many as 300 to 600 sheds per minute, the reciprocating motion of the heddle frame was very rapid and the inertia of the heddle frame, owing to its weight, was very great. This caused frequent breaking of the heddle frames, particularly at the connection between the end braces and the top and bottom rails.
In an attempt to overcome such defects and to reduce the inertia of the heddle frame, the top and bottom rails have been made of light weight hollow aluminum beams. However, the aluminum rails are subjected to substantial bending which exerts a flexing movement on the connection between the end brace and the top and bottom rails. This flexing action results in fatigue of the metal comprising the end braces or the rails or both, thereby causing frequent failure of the heddle frame.
Several attempts have been made to overcome the problems created by the high speed weaving machines. One such attempt is shown in U.S. Pat. No. 4,022,252 issued May 10, 1977 to Hiroshi Ogura. In this patent, the end brace has a metal core, a portion of which is covered with plastic to provide additional strength. A pair of joining pieces project from the strengthened portion of the core of the end brace, as one body and form a tapered groove therebetween. These projections extend into the hollow body of the cross rails. The end brace is anchored to the cross rails by means of a wedge shaped member which is attached to the end brace by screws. The wedge shape member enters the tapered groove, formed by the projecting pieces, so as to force the projecting pieces against the side walls of the cross rail, locking the end brace firmly to the cross rails. This joint is relatively rigid in that the projected pieces are firmly forced against the walls of the cross rail and provides little or no flexibility between the end brace and the cross rails. This arrangement makes for a stronger connection between the end brace and the cross rails but does not provide for the flexibility of the connection which is necessary to avoid unduly flexing or fatiguing the metal making up the end braces or the cross rails.
Another attempt to resolve the defects and deficiencies of the prior art heddle frames is shown in U.S. Pat. No. 4,230,159 issued Oct. 28, 1980 to Yoichi Shimizu. In this patent, the end brace is joined to the cross rail by means of a plastic projection which extends into the hollow space of a cross rail and is pinned to the cross rail by a single pin which permits the projection to pivot about the pin to provide for a flexible joint. A packing material 11 is packed in the space between the end brace and the cross rail to dampen the noise or pivoting action between the end brace and cross rail. This permits flexibility of the joint but it is a design that cannot be readily disassembled for drawing in of the warps or for replacing component parts.
Most of the shortcomings noted above have been overcome in U. S. patent application Ser. No. 06/896,980, However, while the heddle frame of this application overcame and avoided the deficiencies of the prior art, it is not easy to disconnect the end brace from the top or the bottom rail, as the case may be. In one embodiment of the harness frame of this application, it is necessary to remove two bolts at each end connection in order to disconnect the end brace from the projection therefrom or from the sidewalls of the rails. When this was done, it was necessary to store the bolts removed during the disconnection operation and to retain them for later use when the end brace is again attached to the projection.
In another embodiment of said application's harness frame, the projection is made integral with the end brace and is bolted or riveted to the sidewalls of the rail. In order to disconnect the rail from the end brace in this embodiment, it is again necessary to remove the two bolts that hold the projection to the sidewalls of the rail or to knock out the rivets in the case where the rivets are used to connect the projection to the sidewalls. In either case, this becomes a time consuming process and requires the storage of the bolts removed from the rail, and in the case of the rivets, required the insertion of new rivets whenever the end brace was to be fastened to a new rail.